Improvement in liqhtning-rods



D. MUNSON.

Lightning Rod.

No. 100.549. Patented March 8 1870.

fiiinitml fitms DAVID MUNSON, OF INDIANAPOLIS, INDIANA.

Letters Patent No. 100,549, dated March 8, 1870.

IMPROVEMENT IN LIGHTNING-RODS.

The Schedule referred to in the Letters Patent and making part of thesame.

1, DAVID Muxsos, of Indianapolis, in the county of Marion, and State ofIndiana, have invented certain Improvementsin Lightning-Rods, of whichthe following is a specification.

Nature and Objects of the Invention.

Description of the i-lccompanying Drawings.

Figure 1 is a view of a part of two adjacent sections of my improvedlightning-rod.

Figure 2 is aliorizontal section of the rod.

Figure 3 shows the manner of forming the strips before passing themthrough the forming machine.

Similar letters of reference indicate the. same parts in the severalfigures.

The several sections A of which the rod is composed are made up of twoor more thicknesses of thin sheet metal cut in strips of two or threeinches in width, laid together, and first being folded in a U- tbrm, asshown in fig. 3, are then passed through a suitable machine on a rodor.mandrel, which forms them into a tube, with flanges B B on oppositesides, as shown in fig. .2.

The spiral form is given to the flanges by twisting 'the sections on themandrel before withdrawing it.

The object of making the rod of several thicknesses of sheet metal is toincrease the conducting property of the rod by increasing. the surfaceof metal, the conducting property being in proportion to the surface,which, with two thicknesses, is double that of one thickness.

Furthermore, the receiving property of the rod is largely increased byincreasing the number of raw edges of the sheet metal along the rod.

By making the 1. .l of two or more thicknesses the metal may be madethinner, but it will at the same time stitfen the rod without addingmaterially to its weight or cost.

If desired, all the upper part of the rod above the ground may be madeof suitably-plated sheet-iron or other suitable metal, and the partentering the ground of copper or other good conducting, non-oxidizing,durable material, thereby making a cheap and durable lightning-mmductor.

The upper part may be of two or more thicknesses, while the portionunderground may be single, as this is generally in moist earth and doesnot require the increased surface.

Theinside flanged tube is made shorter at each end than the outside one,and the sections are pit together similar to the sections of astove-pipe, the upper end of one section entering the lower end of thesection above it, so that the lower end of the inside tube will restupon the top of the outside tube below, thus forming a smooth closejoint, and avoiding the tendency of the sections to slip into each otherby their weight when the rod is erected.

- The sections are secured together by a wire or narrow strip of thesheet metal passed through holes in the open tlange B at the joining.

Claim.

I claim as my invention- The double tubular sheet-metallightning-conductor with spiral flanges, constructed in sections andjoined together in the manner substantially as and for the purpose setforth.

DAVID MUNSON. Witnesses:

0. 1. MAYrinw, L). W. Kxmninn.

